Absolutize URLs in 404 page.

CSS and images were not loading previously.

Author: BigBlueHat

404.html

@@ -16,15 +16,15 @@
     <meta http-equiv="Content-Type" content="text/html;charset=utf-8" />
 
     <!-- Style Sheets -->
-    <link rel="stylesheet" type="text/css" href="static/css/bootstrap/bootstrap.css">
-    <link rel="stylesheet" type="text/css" href="static/css/bootstrap/bootstrap-responsive.css">
-    <link rel="stylesheet" type="text/css" href="static/css/bootstrap/font-awesome.css">
+    <link rel="stylesheet" type="text/css" href="/static/css/bootstrap/bootstrap.css">
+    <link rel="stylesheet" type="text/css" href="/static/css/bootstrap/bootstrap-responsive.css">
+    <link rel="stylesheet" type="text/css" href="/static/css/bootstrap/font-awesome.css">
     <style>
       /** bootstrap 2.3.2 overrides **/
       .alert.alert-success a {color: #3d9400; text-decoration: underline }
     </style>
 
-    <link rel="shortcut icon" href="favicon.ico" />
+    <link rel="shortcut icon" href="/favicon.ico" />
 
     <!-- Script tags -->
     <script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.0/jquery.min.js"></script>
@@ -53,10 +53,10 @@
           <div class="nav-collapse">
           <ul class="nav">
             <li>
-              <a href="playground/"><span class="icon-beer"></span> Playground</a>
+              <a href="/playground/"><span class="icon-beer"></span> Playground</a>
             </li>
             <li>
-              <a href="learn/"><span class="icon-book"></span> Documentation</a>
+              <a href="/learn/"><span class="icon-book"></span> Documentation</a>
             </li>
             <li><a href="#developers"><span class="icon-beaker"></span> Developers</a></li>
             <li class="dropdown">
@@ -82,7 +82,7 @@
                   <li><a href="/spec/">1.0 drafts (historic)</a></li>
               </ul>
             </li>
-            <li><a href="images/"><span class="icon-picture"></span> Branding</a></li>
+            <li><a href="/images/"><span class="icon-picture"></span> Branding</a></li>
             </ul>
           </div>
           <!--/.nav-collapse -->